Unite said the strikes would not affect summer schemes, but there are fears that an overtime ban could be escalated.

A ballot for industrial action was supported by an overwhelming 97% of union members.

Unite’s Davy Edmont said: “There has been a steady erosion of staff morale since the centres were taken over from Belfast City Council by a company which uses the brand name Better.

“There are a number of issues including pensions and staffing. Our members would say that in some cases safety provision is being reduced, and we are also aware that untrained lifeguards are being employed at some swimming pools.”

One father whose eight-year-old daughter had to complete a 25-yard test said: “This will exclude a number of children from a very important activity that is also a lot of fun for them.”

GLL, the company that took over the centres, insisted the move was for safety reasons.